#1
list1=[1,2,3,2,6,10,1]
a=list1[0]
for i in list1:
    if i>a:
        a=i
print(a)

#2
list2=[1,2,3,4,'a',1,'b',21]
sum=0
for i in list2:
    if isinstance(i,int):
        sum=sum+i
print(sum)

#3
x=5
for i in range(2,x):
    if x%i==0:
        print('不是素数')
        break
else:
    print('是素数')

x=10
sum=0
for i in range(2,x+1):
    for j in range(2,i):
        if i %j==0:
            break
        else:
            sum=sum+1
print(sum)